Studies are proposed in the Bridge Unit C to develop matrix assisted laser desorption ionization (MALDI) as the primary technique of both qualitative and quantitative analysis of lipids extracted from the macrophage. The overall hypothesis centers around the ability to capture HPLC effluents on MALDI plates or similar suitable surfaces such as porous silicon and thereby convert the time domain of HPLC separation to spacial location in a 2-dimensional array. In this way, HPLC separation of lipids required for optimal analysis by both qualitative and quantitative means can be carried out in a parallel step offline from the mass spectrometric analysis. Rapid scanning mass spectrometers with MALDI ion sources can examine the special array for elution of lipids separated by HPLC. In this way sample throughput and lipid analysis would be greatly enhanced. Removing time constraints from the analysis of separated HPLC components should permit both positive and negative ion analysis to be carried out under computer control as well as a detailed analysis of a collision induced decomposition spectra of even minor ions present in complex mixtures of lipids. A second major focus of investigation will be the implementation of qualitative and quantitative assays using MALDI ionization on a high energy TOF/TOF instrument. The inherent rapid scanning of this mass spectrometer as a true tandem instrument should significantly decrease the time required for qualitative analysis of complex mixtures of lipids as well as quantitative analysis of major and minor molecular species. An additional important facet of the TOF/TOF machine is the ability to carry out high energy collision of lipid ions which are proposed to generate new structural information not attainable with low energy collisions with a quadrupole based collision cell. A new dimension of lipid analysis should result. Finally, methods will be developed to automate both qualitative and quantitative aspects of lipid analysis through the generation of specific 3-dimensional arrays of mass spectral and HPLC data. The data array will include retention time, positive or negative molecular ion species, and the complete set of collision induced decomposition ions. These data arrays should be important components of the information available from LIPID MAPS.